Richard Skolnik, lecturing in Yale's Essentials of Global Health course, uses the COVID-19 pandemic as a case study in how public health systems succeed or fail. He walks through the outbreak's early spread, the epidemiological concepts needed to track it such as reproduction number and case fatality rate, and the public health measures countries deployed, from testing and contact tracing to lockdowns and mask mandates. Skolnik compares how different governments responded, weighing the tradeoffs between economic disruption and disease control, and points to gaps in surveillance and health infrastructure that let the virus outrun containment efforts in many places. He also connects COVID to broader themes running through the course: how inequality shapes who gets sick and who gets treated, and why coordinated international action matters more than any single country's response. The lecture is one entry in a long-running Yale course on global health challenges, delivered plainly with slides and direct explanation rather than case dramatization.